Extractor for sheets in ovens



April 1 E. w. MACOY ET AL 2,830,690

EXTRACTOR FOR SHEETS IN OVENS Filed Aug. 14, 1956 3 Sheets-Sheet 1 INVENTORS N EUGENE w. MACOY IF N. BRAGER L /Z K M flaw ATTORNEYS April 15, 1958 I E. W. MACOY ET AL EXTRACTOR FOR SHEETS IN OVENS 5 Sheets-Sheet 2 Filed Aug. 14, 1956 INVENTORS EUGENE w. MACOY LEIF N. BRAGER BY .ZM 27M AT TORNEYS April 15, 1958 E. w. MACOY ET AL 2,830,690

EXTRACTOR FOR SHEETS IN OVENS Filed Aug. 14, 1956 s Sheets-Sheet s 7 Z7474 a7 W INVENTORS EUGENE W. MACOY BY [4 LEIF N. BRAGER slim-Q fifiamm ATTORNEYS United States Patent EXTRACTOR FOR SHEETS 1N OVENS Eugene W. Macoy, Old Greenwich, Conn., and Leif N. Brager, Maplewood, N. J., assignors to American Can Company, New York, N. Y., a corporation of New Jersey Application August 14, 1956, Serial No. 603,889

12 Claims. (Cl. 198-25) The present invention relates to ovens in which freshly coated sheets and the like are dried by heat'and cooling treatments and has particular reference to magnetic extractor devices located at the discharge end of the ovens to facilitate discharge of the dried sheets from the ovens.

An object of the invent-ion is to provide a compact magnetic sheet extractor unit which can be located in the path of travel of the sheets to engage and initiate movement of the sheets to facilitate their discharge from the conveyor which carries them through the oven.

Another object is the provision of such an extractor unit which operates efficiently on large size sheets and under high speed production.

Another object is to provide such an extractor unit which is yieldably mounted so as to provide for a degree of travel with the sheets during their extractions so as to prevent damage to the sheets.

Still another object is to provide for stopping the travel of the conveyor through failure of the extractor unit to perform its function so as to prevent damage to the sheets.

Numerous other objects and advantages of the invention will be apparent as it is better understood from the following description, which, taken in connection with the accompanying drawings, discloses a preferred embodiment thereof.

Referring to the drawings:

Figure l is a top plan view of principal parts of the conveyor discharge end of a sheet drying oven embodying the instant invention, with parts broken away;

Fig. 2 is a sectional view taken substantially along the broken line 22 in Fig. 1, with parts broken away;

Figs. 3, 4 and are enlarged sectional views taken substantially along the respective lines 33, 44, 5-5 in Fig. 1, with parts broken away;

Figs. 6 and 7 are sectional views taken substantially along the respective lines 6-6, 77 in Fig. 3, with parts in Fig. 6 broken away; and

Fig. 8 is a fragmentary sectional view similar to Fig. 3 and showing certain of the parts in a different position.

As a preferred or exemplary embodiment of the instant invention the drawings illustrate a magnetic sheet extractor unit A (Fig. 1) arranged to extract hot, partially cooled coated metallic sheets B from a drying oven of the character extensively used in the can making industry. Such an oven is disclosed in United States Patent 2,395,834 issued March 5, 1946, to W. Bald on Drying Oven.

In such a machine, the sheets B arranged in an inclined on-edge position are-conveyed through the oven on a continuous moving conveyor comprising a pairof spaced and parallel endless chains 21 (Fig. 1) which carry transversely disposed outwardly projecting wickets 22 (see Fig. 2) against which the sheets lean during their travel through the oven. At the discharge end of the oven the conveyor chains 21 operate over a pair of spaced sprockets 23 mounted on a transverse shaft 24 driven in any suitable manner, for example as shown in the above 2 mentioned Bald Patent 2,395,834. This shaft 24 is journaled in bearings 25 on a frame 26 which constitutes a part of the oven.

As the on-edge sheets B approach the discharge end of the oven, they ride up on curved guide rails 28 which extend along the path of travel of the lower edges of the sheets and which curve downwardly and inwardly toward and around the sprocket shaft 24 to permit the inclined sheets to slide on their wickets toward the shaft 24 as the wickets and sheets travel around the shaft from a substantially vertically inclined position to a horizontal position as shown in Fig. 2. This sliding of the sheets B is effected to locate the base of the sheets near the shaft 24 to facilitate extraction by the extractor unit A as will be fully explained hereinafter.

Discharge of the sheets B individually as they appreach the hoizontal position above mentioned, is conventionally effected by a plurality of endless belts 31 which extend into the path of travel of shaped clearance portions of the wickets 22 and which carry the sheets away from the wickets to any suitable place of deposit.

. The belts 31 operate over pulleys 32 suitably supported in an auxiliary frame of the oven and driven in any suitable manner.

However, with the use of extra large sheets and higher speeds of production considerable difficulty has been experienced in overcoming the inertia ofthe sheets fast enough to discharge them by the use of the belts 31. In order to overcome this inertia for the initial movement of the sheets as they approach the discharge position, the instant invention provides a pair of magnetic extractor rolls 35, 36 (Figs. 1 and 2) which are located near the conveyor sprockets 23 and in the path of travel of the sheets adjacent the lower marginal edge portion or base thereof.

The extractor rolls 35, 36 preferably are multimembered units comprising a cylindrical core 37 (Fig. 7) which carries on its outer periphery a permanent magnet ring 38 having at each end thereof an annular pole piece 39 which is larger in diameter than the magnet ring. These members 38, 39 are clamped endwise by an end member 41 against a shoulder 42 on the core 37. A resilient, preferably rubber, tread 43 having ribs or serrations is provided on the outer face of the magnet ring 33 for engagement against the sheets B to initiate their movement.

The extractor rolls 35, 36 preferably are mounted on the outer ends of a continuously rotating shaft 46 (Fig. 7) for rotation therewith. Between the rolls, the shaft 46 is journaled in a pair of anti-friction bearings 47 carried in bearing cages 48 formed on the outer ends of a pair of spaced and parallel arms 49 of a pivot bracket 51 (Fig. 1). The inner ends of the arms 49 are formed with pivot bearings 53 which partially surround the conveyor sprocket shaft 24 and are concentric with the shaft. The bottom portion of each of the bearings is cut away as best shown in Figs. 3 and 5 so as to slip over the shaft from above.

The bearings 53 are supported on and pivot on a stationary pivot sleeve 55 which is concentric with and which partially surrounds the conveyor sprocket shaft 24 in spaced relation thereto as shown in Figs. 3, 4, 5 and 6. The bottom portion of the sleeve is cut away to fit over the shaft from above in the same manner as the bearings 53. This sleeve 55 at its ends is secured in side arms 57 (Figs. 1, 2 and 6) of a bracket 58 secured to the frame 26 of the oven. This bracket 58 and its pivot sleeve 55 carry all of the movable parts of the entire extractor unit.

The extractor rolls 35, 36 are driven by a counterbalanced electric motor 61 (Figs. 2, 3, 6 and 8) which is, suspended from the stationary pivot sleeve 55. Forthis purpose the pivot sleeve 55 supports a counterbalance weight 62 which is provided with a bearing seat 63 (Fig. 4) which fitsaround and rests on the pivot sleeve 55. Adjacent this seat 63, the weight is formed with a pair of depending legs 64 which extend down below the conveyor sprocket shaft 24. These legs 64 carry an inverted U-shaped bracket 65 which supports the electric motor 61.

The counterbalance weight 62 is also secured to the extractor roll bracket 51 by way of a pair of bolts 67 (Figs. 3 and 8) which are threaded into the side of the weight and which extend through elongated slots 68 in a flange 69 on one of the extractor roll bracket bearings 53 (see also Fig. 6). This connection of the counterbalance weight 62 with the extractor roll bracket 51 and the motor 61 provides a compact unit which is readily rocked around the conveyor sprocket shaft 24 without being supported on the shaft and it also provides a yield-v able mounting for the extractor roll. The weight is adjusted, through adjustment of the bolts 67, so that it counterbalances the rest of the unit in such a manner as to hold the extractor rolls 35, 36 in a position with the top portion of their outer periphery just above the horizontal discharge position of the sheets B as shown in Fig.2.

A stop is provided to locate the extractor rolls precisely in this operating position. For this purpose one of the bearings 53 (at the left as viewed in Fig. 6) is formed with a flange 72 (see Fig. having a stop lug 73 which bears against an adjustable set screw '74 threaded into a boss 75 on the adjacent arm 57 of the main bracket 58. A lock nut 76 on the screw is provided to lock the screw in an adjusted position.

In this position of the extractor rolls 35, 36 they are in the path of travel of the sheets B approaching the discharge position, and as soon as a sheet engages the rolls they immediately grip it by reason of their magnetic properties and initiate its discharge movement, pushing the sheet rapidly away from the conveyor chains 21 and advancing it toward the discharge belts 31 to a position where the belts have sufiicient frictional engagement with the sheet to discharge it entirely from its wicket before the next following sheet descends far enough to interfere.

During this initial discharge movement of the sheets,

they are still moving down with the conveyor wickets into their horizontal discharge position and in so doing press down on the extractor rolls 35, 36 and thereby rock the extractor unit on the pivot sleeve 55 in a counterclockwise direction as viewed in the drawings. This rocking movement usually is slight and is intended to v compensate for the movement of the sheet.

However provision is made to stop the conveyor chains 21 and thus stop further advancement of the sheets, if the sheet moving into discharge position is not discharged fast enough and thereby rocks the extractor unit too 4 far. For this purpose the counterbalance weight 62 car ries a stop lug 7 9 (Fig. 3) which normally engages against a switch element 81 of a normally closed electric stop switch 82 connected to wires 83, 84 leading to an electric circuit which includes the oven operating electric motor 85, a normally closed start switch 86, and a source of electric current 67. When the extractor unit swings too far as explained above, when a sheet fails to be discharged by the extractor unit, the stop 79 moves away from the switch element 81 and thereby permits the switch to open. This breaks the circuit and causes the oven motor 85 and hence the oven conveyor chains 21 to stop so that the undischarged sheet may be discharged manually without damaging the sheet or those following.

Continuous rotation of the extractor rolls 35, 36 by thev extractor motor 61 preferably is effected through a variable drive mechanism so as to provide for a selection of speeds of rotation of the rolls under various operating conditions. For this purpose the extractor roll shaft 46 carries a pulley 91 (Figs. 1, 3, and 7) which is rotated by an endless V belt 92. The belt 92 is driven by a conventional variable speed pulley 93 (see also Fig. 6) comprising a fixed disc 94 secured to the rotor shaft 95 of the driving motor 61 and a free disc 96 which is slidable along the rotor shaft 95. The adjacent inner faces of the discs 94, 96 are tapered to receive the V belt 92 between them. The free disc 96 is pressed toward the fixed disc 94 to squeeze the belt between them, by a compression spring 97 which surrounds the rotor shaft 95 and which is interposed between the free disc 96 and a collar 98 secured to the outer end of the rotor shaft.

By changing the distance between the extractor roll shaft 46 and the rotor shaft 95 of the motor 61 the compression spring 97 presses the free disc 96 inwardly for a reduction in the distance or permits the free disc to move outwardly for an increase in the distance and thereby increases or decreases the effective belt driving diammeter of the tapered faces of the discs so as to increase or reduce the speed of rotation of the extractor rolls 35, 36.

This change in distance between the roll shaft 46 and the rotor shaft 95 is efiected by adjustment of the bolts 67 in the slots 68 associated with the counterbalance weight 62. Figs. 3 and 6 show the belt 92 adjusted for normal operation of the mechanism, the bolts 67 being disposed in the middle of the slots 68 in Fig. 3 and the variable pulley 93 in Fig. 6 being adjusted in a median position. In contrast to this, Fig. 8 shows the distance between the roll shaft 46 and the rotor shaft 95 shortened so as to enlarge or increase the effective belt driving diameter of the pulley to increase the speed of the extractor rolls 35, 36. In this Fig. 8, the bolts 67 are at one end of the slots 68 and the belt engages the tapered faces of the variable pulley near their outer peripheries.

It is thought that the invention and many of its attendant advantages will be understood from the foregoing description, and it will be apparent that various changes may be made in the form, construction and arrangement of the parts without departing from the spirit and scope of the invention or sacrificing all of its material advantages, the form hereinbefore described being merely a preferred embodiment thereof.

We claim:

1. In a drying oven for metallic sheets, the combination of a conveyor for carrying sheets through said oven, a magnetic extractor roll, a yieldable mounting for yieldably supporting said roll and biasing it to a normal predetermined position in the path of travel of said sheets for engagement by each sheet individually as said sheet approaches its discharge position on said conveyor, and driving means for rotating said extractor roll to facilitate discharge of said sheets from said conveyor, whereby said roll will yield and move from said normal predetermined position when engaged by a sheet exerting abnormal pressure thereon.

2. In a drying oven of the character defined in claim 1 wherein there is provided a stop switch disposed adjacent said yieldable mounting and electrically connected with means for actuating said conveyor and wherein there is provided stop means movable with said yieldable mounting for actuating said stop switch to stop said conveyor when said yieldable mounting is moved too far by a sheet exerting abnormal pressure on said roll.

3. In a drying oven of the character defined in claim 1 wherein said extractor roll driving means is an electric motor attached to said extractor roll mounting and wherein a counterbalance weight balances said motor and said extractor roll to maintain said roll yieldably in said predetermined position for engagement by said sheets.

4. in a drying oven of the character defined in claim 3 wherein there is provided a variable speed unit between said electric motor and said extractor roll to provide for adjustment of the speed of said roll.

5. In a drying oven of the character defined in claim 1 wherein said yieldable mounting is a pivoted bracket carrying said extractor roll and having a pivot bearing and wherein there is provided a stationary pivot sleeve on which said pivot bearing is freely mounted.

6. In a drying oven of the character defined in claim wherein said conveyor is an endless chain traveling around an axis adjacent the discharge place of said sheets, and wherein said pivot sleeve is disposed in concentricity with said axis.

7. In a drying oven of the character defined in claim 5 wherein a counterbalance weight is seated on said pivot sleeve and is adjustably secured to said pivoted bracket to bias said magnetic extractor roll to said normal predetermined position.

8. In a drying oven of the character defined in claim 5 wherein said conveyor is an endless chain operating over a sprocket on a rotating shaft, and wherein said pivot bearing and said pivot sleeve are adjacently cut away for positioning of said sleeve and said bearing over said shaft.

9. In a drying oven of the character defined in claim 1 wherein said conveyor is provided with wickets for carrying said sheets in an on-edge position and for pivoting said sheets around an axis of said conveyor into a substantially horizontal discharge position and wherein said yieldable mounting is oscillatable and pivoted concentrically'with said axis and said extractor roll is located adjacent the base of a said horizontally positioned sheet remote from said axis to facilitate discharge of said sheet.

10. In a drying oven of the character defined in claim 1 wherein there is.provided stop means partially movable with said yieldable mounting for locating said extractor roll in said normal predetermined position against the force biasing the roll to said position.

11. In a drying oven of the character defined in claim 9 wherein there is provided horizontal discharge means disposed adjacent said conveyor for receiving and discharging said sheets in horizontal position and wherein the top of the outer periphery of said extractor roll is normally disposedadjacent to and in substantially the same plane as said discharge means to initiate movement of said sheets from said conveyor to said discharge means.

12. In a drying oven of the character defined in claim 1 wherein said magnetic extractor roll comprises an annular resilient traction tread interposed between annular magnetic pole pieces, said tread having its traction surface projecting outwardly beyond the peripheries of said pole pieces.

References Cited in the file of this patent UNITED STATES PATENTS 1,770,446 Wilson et al July 15, 1930 

